1. Field of the Invention
This invention relates generally to utilizing moving air as a motive force for generating electric power. More particularly, this invention relates to the utilization of exhaust air flow from one or more ventilation fans which drive windmill type devices having electric power generating means.
2. Description of the Prior Art
Air flow is one of the oldest sources of energy used by man, but even today it is even the least researched suppliers of energy. Moving air in the form of wind has been used as a source of energy to power ships since ancient times. Windmills for purposes of pumping water, grinding corn and other such applications as paper mills and hammer mills date back at least as far as 200 B.C. in Persia. More recently, windmills have been used as a source for generating electrical energy.
The great advantage of wind driven power stations is their environmental friendliness. A wind utilizing power station consumes no raw materials nor does it give off waste gases or waste materials. Furthermore, wind utilizing power devices also produce very little noise in their operation.
Wind utilizing devices of the type having a turbine are known in the industry. Such turbines have blades or vanes attached to a rotatable shaft in which the vanes are driven by the wind and the shaft is coupled to an electric power generating means. These devices are generally referred to as windmills. Such a windmill is described in U.S. Pat. No. 2,004,853 to Crary.
Some such windmills have been specially adapted in an attempt to increase electrical output such as is shown in U.S. Pat. No. 3,720,840 to Gregg. These adoptions include making the position of fluid inlet adjustable so as to be oriented in the direction of the maximum gas flow. Another adaption taught by Gregg includes utilizing a heating unit to increase fluid flow through the device.
Also, attempts have been made to utilize secondary air currents in connection with windmill type devices in order to generate power. For example, in U.S. Pat. No. 3,936,652 to Levine, air inlet ducts of a power plant such as an atomic reactor, a fossil fuel plant, a solar collector or a geothermal heat supply. Thus, as heat flows out of the vertical tower, air is sucked into inlet ducts connected to the cooling tower. As air is sucked into the inlet ducts, it turns the windmill devices provided in such inlet ducts. Similarly, U.S. Pat. No. 1,013,798 to Messina also utilizes inlet air flow of a vertical tower having a heat source disposed therein to drive a windmill type energy generating device.
In each of the above-referenced devices, general wind flow or secondary intake air is captured and converted to energy. None of the cited references disclose capturing exhaust air from air flow producing devices which perform necessary functions.